“Nonsense! Hot air! Balderdash!” blurted out Pavel Kroupa, an astrophysicist at the University of Bonn in Germany, as I stood at the head of the lecture hall. I was just a graduate student at the time, applying for postdoctoral research positions. I had come to Bonn to give a 45-minute talk on my investigations of the small satellite galaxies surrounding the Milky Way. I had helped develop a theory that explains why these mysterious objects are located in what appears to be a straight line stretching across the sky—an unexpected and extremely puzzling alignment. Kroupa, it appeared, was not swayed by my arguments.